Invasion of the Outlanders: Castle from Scotland's Game of Thrones swamped by U.S. fans

HISTORY: Starz is making series with entertainment giants Sony and will first air in the US this summer. [STARZ]

Doune Castle in Perthshire - already a magnet for Monty Python fans - has been flooded with US fans of Outlander, the show dubbed Scotland's answer to "Game of Thrones."

In Outlander the ancient pile, which was used as a set in the Pythons' Holy Grail movie, is the fictional Castle Leoch at the time of the Jacobite Rebellion.

Frustrated producers have been driven barmy by sight-seers interrupting filming as they cannot close the castle off due to Scotland's "right to roam" legislation.

Less than a minute of footage of Outlander has so far been released by cable channel Starz, which is making series with entertainment giants Sony and will first air in the US this summer.

Historic Scotland agreed to close down the 14th century castle itself for filming, but its grounds are being invaded by nosey Yank fans.

SCOTLAND: Less than a minute of footage has been released [STARZ]

Outlander, which will run for 16 episodes over two seasons, is thought to be the biggest ever film or TV production entirely based in Scotland, with a 250-strong cast and crew and a £50 million budget for series one.

It has has won Scottish actor Sam Heughan and Irish actress Caitriona Balfe huge armies of fans - who call themselves Heughligans and Caitriots- around the world after being cast in the show, based on American author Diana Gabaldon's time-travel fantasy books.

Heughan, 33, said: "We are in a bit of bubble here in Scotland, but we went out to Los Angeles for a fan event and heard that they had sold around 2000 tickets. We got there and were treated a bit like rock stars as we had to be driven around the back and people were queuing from 6am to get in.

"I don't think the fans are obsessed with me, they are obsessed with Jamie Fraser, he's such a great character. I didn't really know about the fanbase when I took on the role. But they've been so supportive.

"It feels like we have got on this roller-coaster and have not got off it yet. There is so much in the show - romance, adventure, romance, supernatural stuff, and the whole historic side with the build-up to Culloden.

"It's been great fun, although the whole experience in America was a bit of an eye-opener, but it was great to see the reaction of the fans and the anticipation that's already there."

Catherine Mason, monument manager at Historic Scotland, said: "We can close off the castle, but we can't close off the grounds because of the 'right of way' laws in Scotland.

"We've have a lot of interest from Outlander fans already. The news about the show on twitter is just nuts. They are coming here every single day at the moment. A woman flew here from San Francisco just to see the castle a couple of weeks ago."